Amniotic fluid sTREM-1 in normal pregnancy, spontaneous parturition at term and preterm, and intra-amniotic infection/inflammation

The Role of Innate Immune System in the Human Amniotic Membrane and Human Amniotic Fluid in Protection Against Intra-Amniotic Infections and Inflammation

Intra-amniotic infection and inflammation (IAI) affect fetal development and are highly associated with preterm labor and premature rupture of membranes, which often lead to adverse neonatal outcomes. Human amniotic membrane (hAM), the inner part of the amnio-chorionic membrane, protects the embryo/fetus from environmental dangers, including microbial infection. However, weakened amnio-chorionic membrane may be breached or pathogens may enter through a different route, leading to IAI. The hAM and human amniotic fluid (hAF) respond by activation of all components of the innate immune system. This includes changes in 1) hAM structure, 2) presence of immune cells, 3) pattern recognition receptors, 4) cytokines, 5) antimicrobial peptides, 6) lipid derivatives, and 7) complement system. Herein we provide a comprehensive and integrative review of the current understanding of the innate immune response in the hAM and hAF, which will aid in design of novel studies that may lead to breakthroughs in how we perceive the IAI.

Soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) in neonatal sepsis

BACKGROUND

Efficient and accurate diagnosis of neonatal sepsis is challenging. The potential impact for a reduction in morbidity and mortality as well as antibiotic usage has stimulated the ongoing search for biomarkers of early sepsis. The objective of this pilot study was to quantify the levels of sTREM-1 and correlate with blood cultures and inflammatory markers in neonates evaluated for sepsis.

METHODS

Neonates with suspected sepsis were enrolled (n = 83; Preterm n = 35; Term n = 48). Routine bloods for sepsis evaluation were included and plasma sTREM-1 levels were quantified by ELISA.

RESULTS

Term and preterm neonates (n = 83; Preterm n = 35; Term n = 48) were enrolled and 16 neonates had positive blood cultures (preterm n = 15; term n = 1). sTREM-1 levels were not significantly different in infants with culture-positive or culture-negative sepsis (356 ± 218 pg/mL and 385 ± 254 pg/mL respectively). The immature-to-total granulocyte (I/T) ratio showed a significant positive correlation with sTREM-1 in the preterm group with positive blood cultures. Additionally, sTREM-1 showed a positive correlation with CRP in the preterm group with negative blood cultures.

CONCLUSIONS

sTREM-1 was associated with traditional markers of inflammation (I/T ratio and CRP). However, in this cohort sTREM-1 did not improve the early detection of neonatal culture-positive sepsis.

Diagnostic value of urine soluble triggering receptor expressed on myeloid cells (sTREM-1) for late-onset neonatal sepsis in infected preterm neonates

Objective

Sepsis is a complex clinical condition caused by a dysregulated immune response to an infection resulting in a fatal outcome. This study aimed to investigate the value of urine soluble triggering receptor expressed on myeloid cells (sTREM-1) for diagnosing culture-proven sepsis in preterm infants.

Methods

Preterm neonates were evaluated for late-onset sepsis (LOS). Laboratory investigations were performed. Urine sTREM-1 samples and blood cultures were synchronously collected. Using blood culture results, preterm neonates were divided into the culture-proven group and suspected sepsis group.

Results

A total of preterm 62 infants were included in the study; 31 had culture-proven sepsis and 31 were suspected as having sepsis. There were no significant differences in gestational age, sex, birth weight, and delivery mode between the groups. Neonates in the culture-proven group had significantly higher urine sTREM-1 levels than did those in the suspected sepsis group. Using a cut-off point for a urine sTREM-1 level of 78.5 pg/mL, the sensitivity was 0.90, specificity was 0.78, positive predictive value was 0.68, and negative predictive value was 0.94.

Conclusions

The present study highlights the role of urine sTREM-1 levels in LOS. Urine sTREM-1 may be a reliable and sensitive marker in detecting sepsis in preterm infants.

Hypermethylated CpG sites in the MTR gene promoter in preterm placenta

AIM

Altered maternal one-carbon metabolism influences placental DNA methylation patterns and 'programs' the fetus for noncommunicable diseases in adult life.

EXPERIMENTAL PROCEDURES

Levels of plasma folate, vitamin B₁₂, homocysteine, mRNA and protein levels of MTHFR and MTR enzymes in placenta were compared among women delivering preterm (n = 83) and term (n = 75). MTR promoter CpG methylation was undertaken.

RESULTS

MTHFR and MTR mRNA levels were higher while protein levels were lower, and MTR CpG sites were hypermethylated in the preterm group, as compared with the term group. Methylated CpG sites were negatively associated with maternal plasma vitamin B₁₂ levels.

CONCLUSION

Study suggests a dysregulation of enzyme genes in remethylation arm of the one-carbon metabolism in placenta of women delivering preterm.

CXCL10 and IL-6: Markers of two different forms of intra-amniotic inflammation in preterm labor

Problem

To determine whether amniotic fluid (AF) CXCL10 concentration is associated with histologic chronic chorioamnionitis in patients with preterm labor (PTL) and preterm prelabor rupture of the membranes (PROM).

Method of Study

This study included 168 women who had an episode of PTL or preterm PROM. AF interleukin (IL)‐6 and CXCL10 concentrations were determined by immunoassay.

Results

(i) Increased AF CXCL10 concentration was associated with chronic (OR: 4.8; 95% CI: 1.7‐14), but not acute chorioamnionitis; (ii) increased AF IL‐6 concentration was associated with acute (OR: 4.2; 95% CI: 1.3‐13.7) but not chronic chorioamnionitis; and (iii) an increase in AF CXCL10 concentration was associated with placental lesions consistent with maternal anti‐fetal rejection (OR: 3.7; 95% CI: 1.3‐10.4). (iv) All patients with elevated AF CXCL10 and IL‐6 delivered preterm.

Conclusion

Increased AF CXCL10 concentration is associated with chronic chorioamnionitis or maternal anti‐fetal rejection, whereas increased AF IL‐6 concentration is associated with acute histologic chorioamnionitis.

Expression of TREM-1 in maternal leukocytes in preterm, prelabour rupture of the membranes

Studies have shown that triggering receptor expressed on myeloid cells-1 (TREM-1) is the mediator and activator of neutrophils and monocytes after stimulation with lipopolysaccharide (LPS), heat-inactivated Gram (-) bacteria, Gram (+) bacteria or fungi. Different studies have measured the expression of TREM-1 in patients with bacterial infections and critical states. The purpose of this study was to evaluate the expression of TREM-1 in circulating maternal leukocytes in premature rupture of the membranes (PRM). Two groups of patients were included in this case control study: pregnant women with PRM and healthy controls. All patients were free of any infection, including cervix and urinary tract. Although all patients expressed TREM-1 to some extent, there was no statistically significant difference in the expression of different cellularities in both groups; except for the mononuclear leukocytes (p < 0.05). In this study, TREM-1 was not altered in PRM.

Predictive value of maternal serum NF-κB p65 and sTREM-1 for subclinical chorioamnionitis in premature rupture of membranes

PROBLEM

The aim of this study was to investigate the levels of nuclear factor kappa B-p65 (NF-κB p65) and soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) in maternal blood with premature rupture of membranes (PROM) and to assess their values for prediction of subclinical chorioamnionitis.

METHOD

NF-κB p65 and sTREM-1 levels were measured in maternal blood and cord blood by fluorescence quantitative RT-PCR assay. According to the placental membranes pathological examination, pregnant women with PROM were divided into chorioamnionitis group (n=28) and non-chorioamnionitis group (n=22).

RESULTS

In the PROM group,the NF-κB p65 and sTREM-1 levels in maternal blood were significantly higher in women with chorioamnionitis than women without chorioamnionitis (P<.05). The cutoff value of maternal NF-κB p65, sTREM-1, C-reactive protein (CRP), and WBC level were 6.73, 2.93, 6.75 mg/L, and 10.8×10(9) /L, respectively, through analysis of the area under the ROC curve (AUC). The optimal combination test was detection of maternal blood NF-κB p65 and CRP levels, which resulted in a sensitivity of 89.3% and a specificity of 72.7% for the prediction of subclinical chorioamnionitis.

CONCLUSION

Combined measurements of maternal NF-κB p65 and CRP levels may be used as early biological indicators that predict subclinical chorioamnionitis in premature rupture of membranes.

Accuracy of several maternal seric markers for predicting histological chorioamnionitis after preterm premature rupture of membranes: a prospective and multicentric study

OBJECTIVE

To assess and compare several maternal seric markers for the prediction of histological chorioamnionitis (HCA) after preterm premature rupture of membranes (PPROM). Study design A prospective and multicentric observational study was undertaken, including six French tertiary referral centres. Pregnant women over 18 years, with PPROM between 22+0 and 36+6 WG were enrolled. A blood sample was obtained before delivery and analysed for C-Reactive Protein (CRP), InterCellular Adhesion Molecule-1 (ICAM-1), Interleukin-6 (IL-6), Interleukin-8 (IL-8), Matrix-Metalloproteinase 8 and 9 (MMP-8, MMP-9), Triggering receptor on myeloid cells (TREM-1), and Human Neutrophile Peptides (HNP). HCA was determined by histological examination distinguishing maternal from fetal inflammatory response. Placental analyses and biological assays were performed in duplicate. Comparison of maternal seric markers levels in women with or vs. without HCA was performed, using a non-parametric Receiver Operating Characteristic.

RESULTS

295 women were kept for analysis. The prevalence of HCA was 42.7% (126/295). The concentrations of MMP-8, MMP-9, HNP and CRP were higher in HCA vs. the non-HCA group (P<0.05) whereas the concentrations of ICAM- 1, IL-6, IL-8 were not different (P>0.05). The ROC curve with the largest AUC was for CRP (AUC; 0.70; 95% CI; 0.64-0.77) and it was significantly higher than those for MMP-8, MMP-9, or HNP (P<0.03).

CONCLUSION

CRP was the best maternal marker for predicting HCA in women with PPROM.

About one-half of early spontaneous preterm deliveries can be identified by a rapid matrix metalloproteinase-8 (MMP-8) bedside test at the time of mid-trimester genetic amniocentesis

OBJECTIVE

Mid-trimester amniocentesis continues to be used for the prenatal diagnosis of chromosomal anomalies and other genetic disorders. Analysis of amniotic fluid obtained at the time of mid-trimester genetic amniocentesis identifies those patients who are at risk for early spontaneous preterm delivery. This is based on a solid body of evidence that found subclinical intra-amniotic inflammation/infection to be causally linked to early spontaneous preterm birth. Although several biomarkers have been proposed to identify intra-amniotic inflammation, the accumulated data suggest that the determination of amniotic fluid matrix metalloproteinase-8 (MMP-8), or neutrophil collagenase, is a powerful predictor of spontaneous preterm delivery. MMP-8 is released by inflammatory cells in response to microbial products or "danger signals". A rapid point-of-care test has been developed to determine MMP-8 at the bedside within 20 min, and without the requirement of laboratory equipment. The objective of this study was to determine whether an elevation of MMP-8 in the amniotic fluid, measured by a rapid point-of-care test, can identify those patients at risk for spontaneous preterm delivery after a mid-trimester genetic amniocentesis.

STUDY DESIGN

A case-control study was designed to obtain amniotic fluid from asymptomatic singleton pregnant women who underwent mid-trimester genetic amniocentesis. An MMP-8 bedside test was performed to analyze the amniotic fluid of 64 patients with early spontaneous preterm delivery (<30 weeks) and 128 matched controls with normal pregnancy outcomes.

RESULTS

(1) The MMP-8 bedside test (Yoon's MMP-8 Check™) was positive in 42.2% (27/64) of patients with spontaneous preterm delivery but in none (0/128) of the control cases (p < 0.001); (2) the MMP-8 bedside test had a sensitivity of 42.2%, and a specificity of 100% in the prediction of spontaneous preterm delivery (<30 weeks) following a mid-trimester genetic amniocentesis; and (3) among the patients with spontaneous preterm delivery, those with a positive MMP-8 bedside test had a significantly higher rate of spontaneous delivery within 2 weeks and 4 weeks of an amniocentesis [40.7% (11/27) versus 5.4% (2/37); 63.0% (17/27) versus 24.3% (9/37)] and a shorter interval-to-delivery period than those with a negative test [interval-to-delivery: median (range), 16 d (0-95 d) versus 42 d (2-91 d); p < 0.05 for each].

CONCLUSION

We conclude that 42% of patients with an early spontaneous preterm delivery (< 30 weeks) could be identified by a rapid MMP-8 bedside test at the time of their mid-trimester genetic amniocentesis. The MMP-8 bedside test is a powerful predictor of early spontaneous preterm birth in asymptomatic pregnant women.

A New Triggering Receptor Expressed on Myeloid Cells (TREM) Family Member, TLT-6, is Involved in Activation and Proliferation of Macrophages

The triggering receptor expressed on myeloid cells (TREM) family, which is abundantly expressed in myeloid lineage cells, plays a pivotal role in innate and adaptive immune response. In this study, we aimed to identify a novel receptor expressed on hematopoietic stem cells (HSCs) by using in silico bioinformatics and to characterize the identified receptor. We thus found the TREM-like transcript (TLT)-6, a new member of TREM family. TLT-6 has a single immunoglobulin domain in the extracellular region and a long cytoplasmic region containing 2 immunoreceptor tyrosine-based inhibitory motif-like domains. TLT-6 transcript was expressed in HSCs, monocytes and macrophages. TLT-6 protein was up-regulated on the surface of bone marrow-derived and peritoneal macrophages by lipopolysaccharide stimulation. TLT-6 exerted anti-proliferative effects in macrophages. Our results demonstrate that TLT-6 may regulate the activation and proliferation of macrophages.

A rapid interleukin-6 bedside test for the identification of intra-amniotic inflammation in preterm labor with intact membranes

Objective: Preterm birth is associated with 5–18% of pregnancies and is the leading cause of neonatal morbidity and mortality. Amniotic fluid (AF) interleukin-6 (IL-6) is a key cytokine for the identification of intra-amniotic inflammation, and patients with an elevated AF IL-6 are at risk for impending preterm delivery. However, results of the conventional method of measurement (enzyme-linked immunosorbent assay; ELISA) are usually not available in time to inform care. The objective of this study was to determine whether a point of care (POC) test or lateral-flow-based immunoassay for measurement of AF IL-6 concentrations can identify patients with intra-amniotic inflammation and/or infection and those destined to deliver spontaneously before term among women with preterm labor and intact membranes.

Methods: One-hundred thirty-six women with singleton pregnancies who presented with symptoms of preterm labor and underwent amniocentesis were included in this study. Amniocentesis was performed at the time of diagnosis of preterm labor. AF Gram stain and AF white blood cell counts were determined. Microbial invasion of the amniotic cavity (MIAC) was defined according to the results of AF culture (aerobic and anaerobic as well as genital mycoplasmas). AF IL-6 concentrations were determined by both lateral flow-based immunoassay and ELISA. The primary outcome was intra-amniotic inflammation, defined as AF ELISA IL-6 ≥ 2600 pg/ml.

Results: (1) AF IL-6 concentrations determined by a POC test have high sensitivity (93%), specificity (91%) and a positive likelihood ratio of 10 for the identification of intra-amniotic inflammation by using a threshold of 745 pg/ml; (2) the POC test and ELISA for IL-6 perform similarly in the identification of MIAC, acute inflammatory lesions of placenta and patients at risk of impending spontaneous preterm delivery.

Conclusion: A POC AF IL-6 test can identify intra-amniotic inflammation in women who present with preterm labor and intact membranes and those who will subsequently deliver spontaneously before 34 weeks of gestation. Results can be available within 20 min – this has important clinical implications and opens avenues for early diagnosis as well as treatment of intra-amniotic inflammation/infection.

The relationship between the intensity of intra-amniotic inflammation and the presence and severity of acute histologic chorioamnionitis in preterm gestation

OBJECTIVE

Acute histologic chorioamnionitis (HCA) is associated with an increased risk of perinatal mortality and morbidity. The purpose of this study was to determine the relationship between the intensity of intra-amniotic inflammation (IAI) and the severity of acute HCA in preterm gestation.

METHODS

The relationship between the intensity of IAI and the presence and severity of acute HCA was examined in 412 patients with singleton gestations who delivered within 120 h of transabdominal amniocentesis. The concentration of amniotic fluid (AF) matrix metalloproteinase (MMP)-8 was assayed to determine the presence and intensity of IAI. Acute HCA was defined as the presence of inflammatory change in any tissue samples according to the criteria previously reported. The total grade of acute HCA was used to determine the severity of HCA.

RESULTS

(1) Patients with IAI had a significantly higher rate of acute HCA than those without IAI [76.9% (133/173)] versus 20.9% (50/239), p < 0.001]. The AF MMP-8 concentration was significantly higher in patients with acute HCA than in those without acute HCA (median [range]; 188.3 ng/ml [0.3-6142.6] versus 1.8 ng/ml [0.3-2845.5], p < 0.001); (2) Of 183 patients with acute HCA, the AF MMP-8 concentration was positively correlated with the severity of acute HCA (p < 0.001).

CONCLUSIONS

AF MMP-8 concentration was not only a predictor of the presence of acute HCA, but its concentration also correlated with the severity of acute HCA. The higher the intensity of IAI, the worse the degree of acute HCA in preterm gestation.

Tetrabromobisphenol A activates inflammatory pathways in human first trimester extravillous trophoblasts in vitro

Tetrabromobisphenol A (TBBPA) is a widely used flame retardant. Despite the presence of TBBPA in gestational tissues and the importance of proper regulation of inflammatory networks for successful pregnancy, there is no prior study on the effects of TBBPA on inflammatory responses in gestational tissues. The present study aimed to investigate TBBPA activation of inflammatory pathways, specifically cytokine and prostaglandin production, in the human first trimester placental cell line HTR-8/SVneo. TBBPA enhanced release of interleukin (IL)-6, IL-8, and prostaglandin E2 (PGE2), and suppressed TGF-β release in HTR-8/SVneo cells. The lowest effective concentration was 10 μM TBBPA. A commercial immune response PCR array revealed increased expression of genes involved in inflammatory pathways stimulated by TBBPA in HTR-8/SVneo cells. Because proper regulation of inflammatory mediators in the gestational compartment is necessary for normal placental development and successful pregnancy, further investigation on the impact of TBBPA-stimulated responses on trophoblast function is warranted.

Inflammatory response in maternal serum during preterm labour

Preterm birth (PTB), defined as a delivery before 37 weeks of gestation, is the leading cause of perinatal morbidity and mortality worldwide. Diagnosis of preterm labour as well as accurate prediction of PTB is notoriously difficult. Preterm birth is initiated by multiple mechanisms including infection or inflammation which is the only pathological process for which a firm causal link with PTB has been established. Intrauterine infection evokes an immune response that involves the release of cytokines and chemokines, prostaglandins and matrix-degrading enzymes. These substances trigger uterine contractions, membrane rupture and cervical ripening. Most intra-uterine infections are chronic and subclinical in nature and consequently hard to diagnose before labour or rupture of the membranes. The best studied site of infection is amniotic fluid, but this requires an invasive procedure. A non-invasive approach seems to be more relevant to clinical practice. However, few studies have investigated the maternal inflammatory response during preterm labour. Therefore, the overall objective of this study was to determine several inflammatory markers in maternal serum from pregnant women in labour (either term or preterm) vs. non-labouring controls. We completed a nested case control study in which singleton pregnancies were recruited at Ghent University Hospital and divided into groups according to gestational age and labour status. Multiple proteins were evaluated in maternal serum using enzyme-linked or multiplex bead immunoassays including soluble triggering receptor expressed on myeloid cells-1 (sTREM-1), matrix metalloproteinases (MMP)-9 and MMP-3, tissue inhibitor of metalloproteinases (TIMP)-1, TIMP-2, TIMP-3 and TIMP-4 and a panel of 30 cytokines, chemokines and growth factors.

Soluble ST2, a modulator of the inflammatory response, in preterm and term labor

OBJECTIVE

Intra-amniotic infection/inflammation (IAI) is causally linked with spontaneous preterm labor and delivery. The ST2L receptor and its soluble form (sST2) are capable of binding to interleukin (IL)-33, a member of the IL-1 superfamily. Members of this cytokine family have been implicated in the onset of spontaneous preterm labor in the context of infection. Soluble ST2 has anti-inflammatory properties, and plasma concentrations are elevated in systemic inflammation, such as sepsis, acute pyelonephritis in pregnancy and the fetal inflammatory response syndrome. The aims of this study were to examine: (1) whether amniotic fluid concentrations of sST2 change with IAI, preterm, and term parturition; and (2) if mRNA expression of ST2 in the chorioamniotic membranes changes with acute histologic chorioamnionitis in women who deliver preterm.

METHOD

A cross-sectional study was conducted to determine amniotic fluid concentrations of sST2 in: (1) women with preterm labor (PTL) who delivered at term (n=49); (2) women with PTL who delivered preterm without IAI (n=21); (3) women with PTL who delivered preterm with IAI (n=31); (4) term pregnancies not in labor (n=13); and (5) term pregnancies in labor (n=43). The amniotic fluid concentration of sST2 was determined by ELISA. The mRNA expression of ST2 in the chorioamniotic membranes of women who delivered preterm with (n=24), and without acute histologic chorioamnionitis (n=19) was determined by qRT-PCR.

RESULTS

(1) Patients with PTL who delivered preterm with IAI had a lower median amniotic fluid concentration of sST2 compared to those with PTL who delivered preterm without IAI [median 410 ng/mL, inter-quartile range (IQR) 152-699 ng/mL versus median 825 ng/mL, IQR 493-1216 ng/mL; p=0.0003] and those with PTL who delivered at term [median 410 ng/mL, IQR 152-699 ng/mL versus median 673 ng/mL, IQR 468-1045 ng/mL; p=0.0003]; (2) no significant differences in the median amniotic fluid concentration of sST2 were observed between patients with PTL who delivered at term and those who delivered preterm without IAI (p=0.4), and between women at term in labor and those at term not in labor (p=0.9); (3) the mean mRNA expression of ST2 was 4-fold lower in women who delivered preterm with acute histologic chorioamnionitis than in those without this lesion (p=0.008).

CONCLUSIONS

The median sST2 amniotic fluid concentration and mRNA expression of ST2 by chorioamniotic membranes is lower in PTL associated with IAI and acute histologic chorioamnionitis than in PTL without these conditions. Changes in the median amniotic fluid sST2 concentration are not observed in preterm and term parturition without IAI. Thus, amniotic fluid sST2 in the presence of IAI behaves differently when compared to sST2 in the plasma of individuals affected by fetal inflammatory response syndrome, acute pyelonephritis in pregnancy, and adult sepsis. Decreased concentrations of sST2 in IAI are likely to promote a pro-inflammatory response, which is important for parturition in the context of infection.

Fetal placental inflammation is associated with poor neonatal growth of preterm infants: a case-control study

OBJECTIVE

To determine whether there is an association between histological chorioamnionitis (HCA) and postnatal growth of preterm infants in the neonatal period.

METHOD

This case-control study is part of a larger prospective histological study on placentas performed in all deliveries prior to 32 weeks of gestation. Eligible cases involved all placentas with a diagnosis of HCA. Control subjects were those without HCA, matched 1:1 with case subjects according to gestational age (±1 week). Placental inflammatory status and serial weight gain were analyzed for all infants during the first four postnatal weeks. Based on placental inflammation extension, HCA was defined as maternal HCA (MHCA) or fetal HCA (FHCA).

RESULTS

Of the 320 mother-infant pairs, 71 (22.1%) presented with HCA (27 MHCA and 44 FHCA). Decreases in weight gain at 21 and 28 days were associated with the presence of FHCA (β coefficient ± SE = -4.40 ± 2.21, p = 0.05 and -6.92 ± 2.96, p = 0.02, respectively), whereas no significant differences were found between MHCA and no-HCA groups. FHCA and MHCA were not identified as risk factors of weekly weight gain, after adjusting for possible confounders (maternal ethnicity, parity, smoking during pregnancy, infant gender, IUGR status, SGA status, antenatal steroids, total fluid intake, late-onset sepsis, BPD).

CONCLUSIONS

We found an association between fetal placental inflammation and poor neonatal growth but we were not able to identify a specific week wherein weight gain could be mostly affected. Placental findings may be used to identify preterm infants at risk of postnatal growth failure.

Elevated soluble triggering receptor expressed on myeloid cells (sTREM)-1 levels in maternal serum during term and preterm labor

Background

Infection and inflammation are important mechanisms leading to preterm birth. Soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) belongs to a family of cell surface receptors that seems to play an important role in fine-tuning the immune response. It has been demonstrated that sTREM-1 is involved in bacterial infection as well as in non-infectious inflammatory conditions. Few studies have investigated serum sTREM-1 expression during preterm labor. Therefore, the purpose of this study was to assess sTREM-1 concentrations in maternal serum during term and preterm labor.

Methods

This case control study included 176 singleton pregnancies in the following groups: patients in (1) preterm labor, delivered before 34 weeks (PTB) (n = 52); (2) GA matched controls, not in labor, matched for gestational age (GA) with the PTB group (n = 52); (3) at term in labor (n = 40) and (4) at term not in labor (n = 32). sTREM-1 concentrations were determined by enzyme-linked immunoassay.

Results

sTREM-1 was detected in all serum samples. Median sTREM-1 concentrations were significantly higher in women with PTB vs. GA matched controls (367 pg/ml, interquartile range (IQR) 304–483 vs. 273 pg/ml, IQR 208–334; P<0.001) and in women at term in labor vs. at term not in labor (300 pg/ml, IQR 239–353 vs. 228 pg/ml, IQR 174–285; P<0.001). Women with PTB had significantly higher levels of sTREM-1 compared to women at term in labor (P = 0.004). Multiple regression analysis, with groups recoded as three key covariates (labor, preterm and rupture of the membranes), showed significantly higher sTREM-1 concentrations for labor (+30%, P<0.001) and preterm (+15%, P = 0.005) after adjusting for educational level, history of PTB and sample age.

Conclusions

sTREM-1 concentrations in maternal serum were elevated during spontaneous term and preterm labor and sTREM-1 levels were significantly higher in preterm labor.

Clinical chorioamnionitis is characterized by changes in the expression of the alarmin HMGB1 and one of its receptors, sRAGE

OBJECTIVE

High mobility group box-1 (HMGB1) protein is an alarmin, a normal cell constituent, which is released into the extracellular environment upon cellular stress/damage and capable of activating inflammation and tissue repair. The receptor for advanced glycation end products (RAGE) can bind HMGB1. RAGE, in turn, can induce the production of pro-inflammatory cytokines; this may be modulated by the soluble truncated forms of RAGE, including soluble RAGE (sRAGE) and endogenous secretory RAGE (esRAGE). The objectives of this study were to determine whether: 1) clinical chorioamnionitis at term is associated with changes in amniotic fluid concentrations of HMGB1, sRAGE and esRAGE; and 2) the amniotic fluid concentration of HMGB1 changes with labor or as a function of gestational age.

METHODS

Amniotic fluid samples were collected from the following groups: 1) mid-trimester (n = 45); 2) term with (n = 48) and without labor (n = 22) without intra-amniotic infection; and 3) term with clinical chorioamnionitis (n = 46). Amniotic fluid concentrations of HMGB1, sRAGE and esRAGE concentrations were determined by ELISA.

RESULTS

1) the median amniotic fluid HMGB1 concentration was higher in patients at term with clinical chorioamnionitis than in those without this condition (clinical chorioamnionitis: median 3.8 ng/mL vs. term in labor: median 1.8 ng/mL, p = 0.007; and vs. term not in labor: median 1.1 ng/mL, p = 0.003); 2) in contrast, patients with clinical chorioamnionitis had a lower median sRAGE concentration than those without this condition (clinical chorioamnionitis: median 9.3 ng/mL vs. term in labor: median 18.6 ng/mL, p = 0.001; and vs. term not in labor median: 28.4 ng/mL, p < 0.001); 3) amniotic fluid concentrations of esRAGE did not significantly change in patients with clinical chorioamnionitis at term (clinical chorioamnionitis: median 5.4 ng/mL vs. term in labor: median 6.1 ng/mL, p = 0.9; and vs. term not in labor: median 9.5 ng/mL, p = 0.06); and 4) there was no significant difference in the median AF HMGB1 concentration between women at term in labor and those not in labor (p = 0.4) and between women in the mid-trimester and those at term not in labor (mid-trimester: median 1.5 ng/mL; p = 0.2).

CONCLUSION

An increase in the amniotic fluid HMGB1 concentration and a decrease in sRAGE were observed in clinical chorioamnionitis at term. This finding provides evidence that an alarmin, HMGB1, and one of its receptors, sRAGE, are engaged in the process of clinical chorioamnionitis at term. These changes are quite different from those observed in cases of intra-amniotic infection/inflammation in preterm gestations.

Value of soluble TREM-1, procalcitonin, and C-reactive protein serum levels as biomarkers for detecting bacteremia among sepsis patients with new fever in intensive care units: a prospective cohort study

Background

The purpose of this study was to explore the diagnostic value of soluble triggering receptor expressed on myeloid cells 1 (sTREM-1), procalcitonin (PCT), and C-reactive protein (CRP) serum levels for differentiating sepsis from SIRS, identifying new fever caused by bacteremia, and assessing prognosis when new fever occurred.

Methods

We enrolled 144 intensive care unit (ICU) patients: 60 with systemic inflammatory response syndrome (SIRS) and 84 with sepsis complicated by new fever at more than 48 h after ICU admission. Serum sTREM-1, PCT, and CRP levels were measured on the day of admission and at the occurrence of new fever (>38.3°C) during hospitalization. Based on the blood culture results, the patients were divided into a blood culture-positive bacteremia group (33 patients) and blood culture-negative group (51 patients). Based on 28-day survival, all patients, both blood culture-positive and -negative, were further divided into survivor and nonsurvivor groups.

Results

On ICU day 1, the sepsis group had higher serum sTREM-1, PCT, and CRP levels compared with the SIRS group (P <0.05). The areas under the curve (AUC) for these indicators were 0.868 (95% CI, 0.798–0.938), 0.729 (95% CI, 0.637–0.821), and 0.679 (95% CI, 0.578–0.771), respectively. With 108.9 pg/ml as the cut-off point for serum sTREM-1, sensitivity was 0.83 and specificity was 0.81. There was no statistically significant difference in serum sTREM-1 or PCT levels between the blood culture-positive and -negative bacteremia groups with ICU-acquired new fever. However, the nonsurvivors in the blood culture-positive bacteremia group had higher levels of serum sTREM-1 and PCT (P <0.05), with a prognostic AUC for serum sTREM-1 of 0.868 (95% CI, 0.740–0.997).

Conclusions

Serum sTREM-1, PCT, and CRP levels each have a role in the early diagnosis of sepsis. Serum sTREM-1, with the highest sensitivity and specificity of all indicators studied, is especially notable. sTREM-1, PCT, and CRP levels are of no use in determining new fever caused by bacteremia in ICU patients, but sTREM-1 levels reflect the prognosis of bacteremia.

Trial registration

ClinicalTrial.gov identifier NCT01410578

Serum sTREM-1 (soluble triggering receptor expressed on myeloid cells-1) associates negatively with embryo quality in infertility patients

PROBLEM

Soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) is a useful biomarker of infection and inflammation.

METHOD OF STUDY

We studied serum and follicular fluid sTREM-1 in infertile patients (N = 110) utilizing enzyme-linked immunosorbent assay.

RESULTS

Serum and follicular sTREM-1 were in good correlation (Pearson's correlation 0.56, P < 0.0001) with higher values in follicular fluid (140.4 ± 34.4 and 115.6 ± 35.1 pg/mL, t-test, P < 0.0001). Endometriosis associated with lower follicular and serum sTREM-1 compared with male factor infertility patients (age-adjusted r = -25.7 pg/mL, P = 0.018; r = -22.1 pg/mL, P = 0.030). No associations between follicular or serum sTREM-1 and clinical parameters were found, except higher serum sTREM-1 associated with lower embryo quality in all patients (adjusted r = -0.3%, P = 0.033), with a cutoff value between 111.5 and 113.3 pg/mL (OR = 0.38, P = 0.048; OR = 0.34, P = 0.028) predicting that more than 39% of embryos would be with good quality.

CONCLUSION

Serum sTREM-1 could represent a prognostic marker for female fecundity, probably indicating impaired inflammatory reaction of immune system.

Blood pH and gases in fetuses in preterm labor with and without systemic inflammatory response syndrome

OBJECTIVE

Fetal hypoxemia has been proposed to be one of the mechanisms of preterm labor (PTL) and delivery. This may have clinical implications since it may alter: (i) the method/frequency of fetal surveillance and (ii) the indications and duration of tocolysis to an already compromised fetus. The aim of this study was to examine whether there is a difference in the fetal blood gas analysis [pH, PaO(2) and base excess (BE)] and in the prevalence of fetal acidemia and hypoxia between: (i) patients in PTL who delivered within 72 hours vs. those who delivered more than 72 hours after cordocentesis and (ii) patients with fetal inflammatory response syndrome (FIRS) vs. those without this condition.

STUDY DESIGN

Patients admitted with PTL underwent amniocentesis and cordocentesis. Ninety women with singleton pregnancies and PTL were classified according to (i) those who delivered within 72 hours (n = 30) and after 72 hours of the cordocentesis (n = 60) and (ii) with and without FIRS. FIRS was defined as a fetal plasma concentration of IL-6 > 11 pg/mL. Fetal blood gases were determined. Acidemia and hypoxemia were defined as fetal pH and PaO(2) below the 5th percentile for gestational age, respectively. For comparisons between the two study groups, ΔpH and ΔPaO(2) were calculated by adjusting for gestational age (Δ = observed value - mean for gestational age). Non-parametric statistics were employed.

RESULTS

No differences in the median Δ pH (-0.026 vs. -0.016), ΔPaO(2) (0.25 mmHg vs. 5.9 mmHg) or BE (-2.4 vs. -2.6 mEq/L) were found between patients with PTL who delivered within 72 hours and those who delivered 72 hours after the cordocentesis (p > 0.05 for all comparisons). Fetal plasma IL-6 concentration was determined in 63% (57/90) of fetuses and the prevalence of FIRS was 28% (16/57). There was no difference in fetal pH, PaO(2) and BE between fetuses with and without FIRS (p > 0.05 for all comparisons). Moreover, there was no difference in the rate of fetal acidemia between fetuses with and without FIRS (6.3 vs. 9.8%; p > 0.05) and fetal hypoxia between fetuses with or without FIRS (12.5 vs. 19.5%; p > 0.05).

CONCLUSIONS

Our data do not support a role for acute fetal hypoxemia and metabolic acidemia in the etiology of PTL and delivery.

Diagnostic value of urine sTREM-1 for sepsis and relevant acute kidney injuries: a prospective study

Introduction

We explored the diagnostic value of a urine soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) for early sepsis identification, severity and prognosis assessment, and for secondary acute kidney injury (AKI). We compared this with white blood cell (WBC) counts, serum C-reactive protein (CRP), serum procalcitonin (PCT), urine output, creatinine clearance (CCr), serum creatinine (SCr), and blood urea nitrogen (BUN).

Methods

We enrolled 104 subjects admitted to the ICU: 16 cases with systemic inflammatory response syndrome (SIRS); 35 with sepsis and 53 with severe sepsis. Results for urine sTREM-1, WBC, serum CRP and serum PCT were recorded on days 1, 3, 5, 7, 10, and 14. For 17 sepsis cases diagnosed with secondary AKI, comparisons between their urine sTREM-1, urine output, CCr, SCr and BUN at diagnosis and 48 h before diagnosis were made.

Results

On the day of admission to the ICU, and compared with the SIRS group, the sepsis group exhibited higher levels of urine sTREM-1 and Acute Physiologic Assessment and Chronic Health Evaluation II (APACHE II) scores (P < 0.05). Areas under the curve (AUC) shaped by the scores were 0.797 (95% CI 0.711 to 0.884) and 0.722 (95% CI 0.586 to 0.858), respectively. On days 1, 3, 5, 7, 10, and 14, urine sTREM-1, serum PCT and WBC levels registered higher in the severe sepsis group in contrast to the sepsis group (P < 0.05). Urine sTREM-1 and serum PCT levels continuously increased among non-survivors, while WBC and serum CRP levels in both groups declined. For 17 patients with AKI, urine sTREM-1, SCr and BUN levels at 48 h before AKI diagnosis were higher, and CCr level was lower than those for non-AKI subjects (P < 0.05). AUC for urine sTREM-1 was 0.922 (95% CI 0.850 to 0.995), the sensitivity was 0.941, and the specificity was 0.76 (based on a cut-off point of 69.04 pg/ml). Logistic regression analysis showed that urine sTREM-1 and severity were risk factors related to AKI occurrence.

Conclusions

Besides being non-invasive, urine sTREM-1 testing is more sensitive than testing WBC, serum CRP, and serum PCT for the early diagnosis of sepsis, as well as for dynamic assessments of severity and prognosis. It can also provide an early warning of possible secondary AKI in sepsis patients.

Trial Registration

ClinicalTrial.gov identifier NCT01333657

Hematologic profile of the fetus with systemic inflammatory response syndrome

OBJECTIVE

The fetal inflammatory response syndrome (FIRS) is associated with impending onset of preterm labor/delivery, microbial invasion of the amniotic cavity and increased perinatal morbidity. FIRS has been defined by an elevated fetal plasma interleukin (IL)-6, a cytokine with potent effects on the differentiation and proliferation of hematopoietic precursors. The objective of this study was to characterize the hematologic profile of fetuses with FIRS.

STUDY DESIGN

Fetal blood sampling was performed in patients with preterm prelabor rupture of membranes and preterm labor with intact membranes (n=152). A fetal plasma IL-6 concentration ≥ 11 pg/mL was used to define FIRS. Hemoglobin concentration, platelet count, total white blood cell (WBC) count, differential count, and nucleated red blood cell (NRBC) count were obtained. Since blood cell count varies with gestational age, the observed values were corrected for fetal age by calculating a ratio between the observed and expected mean value for gestational age.

RESULTS

1) The prevalence of FIRS was 28.9% (44/152); 2) fetuses with FIRS had a higher median corrected WBC and corrected neutrophil count than those without FIRS (WBC: median 1.4, range 0.3-5.6, vs. median 1.1, range 0.4-2.9, P=0.001; neutrophils: median 3.6, range 0.1-57.5, vs. median 1.8, range 0.2-13.9, P<0.001); 3) neutrophilia (defined as a neutrophil count >95th centile of gestational age) was significantly more common in fetuses with FIRS than in those without FIRS (71%, 30/42, vs. 35%, 37/105; P<0.001); 4) more than two-thirds of fetuses with FIRS had neutrophilia, whereas neutropenia was present in only 4.8% (2/42); 5) FIRS was not associated with detectable changes in hemoglobin concentration, platelet, lymphocyte, monocyte, basophil or eosinophil counts; and 6) fetuses with FIRS had a median corrected NRBC count higher than those without FIRS. However, the difference did not reach statistical significance (NRBC median 0.07, range 0-1.3, vs. median 0.04, range 0-2.3, P=0.06).

CONCLUSION

The hematologic profile of the human fetus with FIRS is characterized by significant changes in the total WBC and neutrophil counts. The NRBC count in fetuses with FIRS tends to be higher than fetuses without FIRS.

Damage-associated molecular patterns (DAMPs) in preterm labor with intact membranes and preterm PROM: a study of the alarmin HMGB1

OBJECTIVE

Preterm parturition is a syndrome caused by multiple etiologies. Although intra-amniotic infection is causally linked with intrauterine inflammation and the onset of preterm labor, other patients have preterm labor in the absence of demonstrable infection. It is now clear that inflammation may be elicited by activation of the Damage-Associated Molecular Patterns (DAMPs), which include pathogen-associated molecular patterns (PAMPs) as well as "alarmins" (endogenous molecules that signal tissue and cellular damage). A prototypic alarmin is high-mobility group box 1 (HMGB1) protein, capable of inducing inflammation and tissue repair when it reaches the extracellular environment. HMGB1 is a late mediator of sepsis, and blockade of HMGB1 activity reduces mortality in an animal model of endotoxemia, even if administered late during the course of the disorder. The objectives of this study were to: (1) determine whether intra-amniotic infection/inflammation (IAI) is associated with changes in amniotic fluid concentrations of HMGB1; and (2) localize immunoreactivity of HMGB1 in the fetal membranes and umbilical cord of patients with chorioamnionitis.

METHODS

Amniotic fluid samples were collected from the following groups: (1) preterm labor with intact membranes (PTL) with (n=42) and without IAI (n=84); and (2) preterm prelabor rupture of membranes (PROM) with (n=38) and without IAI (n=35). IAI was defined as either a positive amniotic fluid culture or amniotic fluid concentration of interleukin-6 (IL-6) ≥ 2.6ng/mL. HMGB1 concentrations in amniotic fluid were determined by ELISA. Immunofluorescence staining for HMGB1 was performed in the fetal membranes and umbilical cord of pregnancies with acute chorioamnionitis.

RESULTS

(1) Amniotic fluid HMGB1 concentrations were higher in patients with IAI than in those without IAI in both the PTL and preterm PROM groups (PTL IAI: median 3.1 ng/mL vs. without IAI; median 0.98 ng/mL; p <0.001; and preterm PROM with IAI median 7.3 ng/mL vs. without IAI median 2.6 ng/mL; p=0.002); (2) patients with preterm PROM without IAI had a higher median amniotic fluid HMGB1 concentration than those with PTL and intact membranes without IAI (p <0.001); and (3) HMGB1 was immunolocalized to amnion epithelial cells and stromal cells in the Wharton's jelly (prominent in the nuclei and cytoplasm). Myofibroblasts and macrophages of the chorioamniotic connective tissue layer and infiltrating neutrophils showed diffuse cytoplasmic HMGB1 immunoreactivity.

CONCLUSIONS

(1) intra-amniotic infection/inflammation is associated with elevated amniotic fluid HMGB1 concentrations regardless of membrane status; (2) preterm PROM was associated with a higher amniotic fluid HMGB1 concentration than PTL with intact membranes, suggesting that rupture of membranes is associated with an elevation of alarmins; (3) immunoreactive HMGB1 was localized to amnion epithelial cells, Wharton's jelly and cells involved in the innate immune response; and (4) we propose that HMGB1 released from stress or injured cells into amniotic fluid may be responsible, in part, for intra-amniotic inflammation due to non-microbial insults.

The frequency of meconium-stained amniotic fluid increases as a function of the duration of labor

OBJECTIVE

The purpose of this study was to determine whether there is a relationship between the frequency of meconium-stained amniotic fluid (MSAF) and the duration of labor in term singleton gestation.

METHODS

The clinical characteristics of women who delivered term singleton live newborns between 2001 and 2006 were examined. The cases involving neonates with major congenital anomalies were excluded.

RESULTS

(1) The frequency of MSAF in term pregnancies was 18.4% (806/4376); (2) MSAF was found in only 2.8% (28/1008) of women who delivered by elective cesarean, but in 23.1% (778/3368) of women who delivered after the onset of labor (p < 0.001); (3) The longer the duration of labor (first stage, second stage, or total), the higher the frequency of MSAF (p < 0.001 for each); this remained significant after adjusting for other confounding variables such as parity, duration of rupture of membranes, gestational age at delivery, and mode of delivery (p < 0.001 for each).

CONCLUSION

MSAF was found in only 2.8% (28/1008) of women who delivered before the onset of labor, but in 23.1% (778/3368) of women who delivered after the onset of labor. The longer the duration of labor, the higher the risk of MSAF in term singleton gestation.

Unique alterations in infection-induced immune activation during pregnancy

BACKGROUND

Immune responses to infection are uniquely regulated during gestation to allow for antimicrobial defence and tissue repair, whilst preventing damage to developing fetal organs or the triggering of preterm labour.

OBJECTIVE

A review and analysis of studies delineating gestation-specific immune modulation and intra-amniotic regulation of pro-inflammatory immunity.

SEARCH STRATEGY

Identification of the alterations between the fetus/neonate and adult with regard to the endogenous and infection-induced expression of molecules with immune regulatory properties, and the characterisation of intra-amniotic immune mediators that inhibit bacterial-induced pro-inflammatory cytokine production.

SELECTION CRITERIA

English and non-English publications from 1985 to the present.

DATA COLLECTION AND ANALYSIS

An electronic literature search using MEDLINE, PubMed, articles cited in the primary sources, as well as pregnancy-related immunology research from our laboratory at Weill Medical College of Cornell University.

MAIN RESULTS

During fetal development, interleukin (IL)-23, IL-10 and IL-6, as well as T-helper-17 (Th17)-mediated immune responses, are upregulated, whereas tumour necrosis factor-α (TNF-α) and IL-1β- and Th1-mediated immune responses are downregulated in the intrauterine environment (both the fetal compartment and the amniotic compartment). Infection-related immunity during gestation is preferentially directed towards combating extracellular microbial pathogens. Amniotic fluid and the neonatal circulation contain multiple components that improve the ability of the developing neonate to tolerate microbial-induced immune activation.

CONCLUSIONS

The repertoire of immune mechanisms to control infection and inflammation differ between fetal and adult life. The dual mechanisms of resistance to infection and tolerance to infection-induced immune activation prevent damage to the developing fetus and the triggering of premature labour.

Metabolomics in premature labor: a novel approach to identify patients at risk for preterm delivery

OBJECTIVE

Biomarkers for preterm labor (PTL) and delivery can be discovered through the analysis of the transcriptome (transcriptomics) and protein composition (proteomics). Characterization of the global changes in low-molecular weight compounds which constitute the 'metabolic network' of cells (metabolome) is now possible by using a 'metabolomics' approach. Metabolomic profiling has special advantages over transcriptomics and proteomics since the metabolic network is downstream from gene expression and protein synthesis, and thus more closely reflects cell activity at a functional level. This study was conducted to determine if metabolomic profiling of the amniotic fluid can identify women with spontaneous PTL at risk for preterm delivery, regardless of the presence or absence of intraamniotic infection/inflammation (IAI).

STUDY DESIGN

Two retrospective cross-sectional studies were conducted, including three groups of pregnant women with spontaneous PTL and intact membranes: (1) PTL who delivered at term; (2) PTL without IAI who delivered preterm; and (3) PTL with IAI who delivered preterm. The first was an exploratory study that included 16, 19, and 20 patients in groups 1, 2, and 3, respectively. The second study included 40, 33, and 40 patients in groups 1, 2, and 3, respectively. Amniotic fluid metabolic profiling was performed by combining chemical separation (with gas and liquid chromatography) and mass spectrometry. Compounds were identified using authentic standards. The data were analyzed using discriminant analysis for the first study and Random Forest for the second.

RESULTS

(1) In the first study, metabolomic profiling of the amniotic fluid was able to identify patients as belonging to the correct clinical group with an overall 96.3% (53/55) accuracy; 15 of 16 patients with PTL who delivered at term were correctly classified; all patients with PTL without IAI who delivered preterm neonates were correctly identified as such (19/19), while 19/20 patients with PTL and IAI were correctly classified. (2) In the second study, metabolomic profiling was able to identify patients as belonging to the correct clinical group with an accuracy of 88.5% (100/113); 39 of 40 patients with PTL who delivered at term were correctly classified; 29 of 33 patients with PTL without IAI who delivered preterm neonates were correctly classified. Among patients with PTL and IAI, 32/40 were correctly classified. The metabolites responsible for the classification of patients in different clinical groups were identified. A preliminary draft of the human amniotic fluid metabolome was generated and found to contain products of the intermediate metabolism of mammalian cells and xenobiotic compounds (e.g. bacterial products and Salicylamide).

CONCLUSION

Among patients with spontaneous PTL with intact membranes, metabolic profiling of the amniotic fluid can be used to assess the risk of preterm delivery in the presence or absence of infection/inflammation.